In the third Generation Partnership Project Long Term Evolution (3GPP LTE) system, uplink resource allocation takes a physical resource block (PRB for short) as a unit. One PRB occupies NSCRB continuous subcarriers in frequency domain, and occupies NsymbUL continuous subcarriers in time domain. NSCRB=12, and a subcarrier interval is 15 kHz, that is, the width of a PRB in frequency domain is 180 kHz. For a normal cyclic prefix (Normal CP for short), NsymbUL=7, and for an extended cyclic prefix (Extended CP for short), NsymbUL=6, that is, the length of a PRB in time domain is a slot (0.5 ms). Thus, a PRB comprises NsymbUL×NSCRB resource elements (RE for short). In one slot, an index of a PRB is nPRB, where nPRB=0, . . . , NRBUL−1, and NRBUL is the number of PRBs corresponding to the uplink system bandwidth; an index pair of a RE is (k,l), where k=0, . . . , NRBULNscRB−1 is an index in frequency domain, and l=0, . . . , NsymbUL−1 is an index in time domain, then
      n    PRB    =      ⌊          k              N        SC        RB              ⌋  
Taking the normal CP as an example, the structure of the PRB is shown in FIG. 1.
As shown in FIG. 2, in the LTE system, Physical Uplink Shared Channels (PUSCH) of a plurality of User Equipments (UE) in a cell frequency-division multiplex the uplink system bandwidth, that is, the PUSCHs of different UEs are orthogonal in frequency domain and occupy different physical resource blocks. However, resource allocation uses a localized allocation method, that is, the PUSCH of one UE occupies a section of continuous bandwidth in frequency domain, which is a part of the entire uplink system bandwidth. The section of bandwidth contains a set of continuous PRBs, the number of which is MRBPUSCH, and the number of its contained continuous subcarriers isMscPUSCH=MRBPUSCH·NscRB 
Uplink reference signals in the LTE system are divided into demodulation reference signals (DM RS) and Sounding Reference Signals (SRS). The DM RSs are further divided into DM RSs for the PUSCH and DM RSs for the Physical Uplink Control Channel (PUCCH). All the uplink reference signals are reference signal sequences in the same form.
An uplink reference signal sequence ru,v(α)(n) in the LTE system is defined as cyclic shift of a base sequence ru,v(n)ru,v(α)(n)=ejan ru,v(n),0≦n≦MscRS−1
where MRscRS=mNscRB is the length of the reference signal sequence, 1≦m≦NRBmax,UL. A different cyclic shift quantity α is used for the base sequence ru,v(n), and a plurality of reference signal sequences can be defined.
The definition of the base sequence ru,v(n) depends on the sequence length MscRS.
If MscRS≧3NscRB, ru,v(n)=xq(n mod NZCRS),0≦n≦MscRS−1
where the qth Zadoff-Chu sequence (ZC sequence for short) is defined as
                    x        q            ⁡              (        m        )              =          ⅇ                        -          j                ⁢                              π            ⁢                                                  ⁢                          qm              ⁡                              (                                  m                  +                  1                                )                                                          N            ZC            RS                                ,      0    ≤    m    ≤                  N        ZC        RS            -      1      
and q is given by the following equation,q=└ q+1/2┘+v·(−1)└2 q┘ q=NZCRS·(u+1)/31
the length NZCRS of the ZC sequence is the largest prime number satisfying NZCRS<MscRS, that is, the ZC sequence with the length of NZCRS forms the base sequence with the length of MscRS by cyclic shift.
If MscRS=NscRB or MscRS=2NscRB, ru,v(n)=ejφ(n)π/4,0≦n≦MscRS−1where values of φ(n) are given in Table 1 and Table 2 respectively.
TABLE 1uφ(0), . . . , φ(11)0−113−3331131−33111333−11−3−31−33211−3−3−3−1−3−31−31−13−11111−1−3−31−33−14−131−11−1−3−11−11351−33−1−111−1−13−316−13−3−3−331−133−317−3−1−1−11−33−11−33181−331−1−1−1113−1191−3−133−1−31111110−13−111−3−3−1−3−33−11131−1−133−313133121−311−3111−3−3−311333−33−3113−1−33314−31−1−3−131333−11153−11−3−1−11131−1−316131−11333−1−13−117−3113−33−3−3313−118−3311−31−3−3−1−11−319−13131−1−13−3−1−3−120−1−3111131−11−3−121−13−11−3−3−3−3−31−1−32211−3−3−3−3−13−31−332311−1−3−1−31−113−1124113133−11−1−3−31251−3331331−3−1−132613−3−33−31−1−13−1−327−3−1−3−1−331−113−3−328−13−33−133−333−1−1293−3−3−1−1−3−13−331−1
TABLE 2uφ(0), . . . , φ(23)0 −13 1−33−113−3313−3311−113−33−3−1−31 −3 3 −3−3 −31−3−33−11113 1−1 3−3−31 311−323 −133 1 1−3 3 3 331−13−111−1−3−1−11 3 33 −1 −311 3 −311−3 −1−1 131 3 1 −131 1 −3−1−3−14 −1 −1−1−3−3−11133−13−1 1 −1−3 1−1−3−3 1 −3 −1−15 −3 113 −113 1 −3 1 −31 1−1 −13 −1−33−3−3−3 1161 1 −1−13 −3−33 −3 1 −1−1 1 −1 1 1−1−3−1 1 −1 3−1−37 −33 3 −1 −1−3−131 3 1311 −131−1 1 3−3−1−118 −3 1 3 −3 1−1−3 3 −33−1−1 −1−1 1 −3−3−3 1−3 −3−31−391 1 −333 −1−3−1 3 −3333−1 1 1 −31 −11 1 −31 110−11 −3−3 3−1 3 −1−1−3−3−3 −1−3−31−1 133 −11−1311 1 3 3 −3 −313 1−1 −3−3−333−333 −1−3 3 −11−3112 1 3 3111 −1 −1 1 −33−111−333−1−3 3 −3−1 −3−113 3 −1−1−1 −1−3−1 33 1 −1 1333−11 1−313−1−3314−3 −33131 −3 31 311 33−1−1−31 −3−1 311315−1 −11 −3 13 −3 1−1 −3−1313 1−1−3 −3−1−1 −3−3 −3−116−1 −33 −1 −1−1−1 11−331 33 1−11−3 1−3 11 −3−117 1 3 −1 3 3 −1−31 −1−3333−1 1 13−1−3−1 3−1 −1−118 1 1 111 −13 −1−3113−31 −3−11 1 −3−331 1 −319 1 3 31 −1−3 3 −1 333−3 1−11 −1−3−1 13−1 3−3−320−1 −33 −3 −3−3−1−1−3−1−3 313−3−13 −1 1−1 3 −3 1−121−3 −311−11 −1 1−13 1 −3 −1 1−11−1 −1 33 −3−11 −322−3 −1−3 3 1−1−3 −1−3 −33 −33−3−1131 −31 33−1−323−1 −1−1−1 3 33 13 3−3 1 3−13 −13 3 −3 31−1 3324 1 −133−1−3 3 −3−1 −13 −13 −1 −11111 −1−1−3 −1325 1−11−13 −13 11 −1−1−311−313 −3 11−3−3 −1−126−3 −113 1 1−3−1−1−33−3 31 −33−31 −11 −311 127−1 −333 113−1−3−1−1−131 −3−3 −13−3−1−3−1−3−128−1 −3−1−11−3−1 −11−1−311−31−3 −3311 −13−1−129 1 1−1−1−3−13 −1 3 −1131−1313−3−31 −1−113
The base sequence ru,v(n) is divided into 30 groups, uε{0, 1, . . . , 29} is a group serial number, and v is an intragroup sequence serial number. Each group contains base sequences with all lengths from MscRS=NscRB to MscRS=NRBmax,UL·NscRB, where there is only one base sequence (v=0) with sequence length satisfying NscRB≦MscRS≦5NscRB for each length, and there are two base sequences (v=0, 1) with sequence length satisfying 6NscRB≦MscRS≦NRBmax,UL·NscRB for each length. The group serial number u and the intragroup sequence serial number v may vary with the time to achieve group hopping and sequence hopping.
The group serial number u of the base sequence used in a slot ns is defined by a group hopping pattern fgh(ns) and a sequence-shift pattern fss according to the following equationu=(fgh(ns)+fss)mod 30
There are 17 group hopping patterns and 30 sequence-shift patterns.
The group hopping function can notify the high layer signaling to turn on or off. The group hopping pattern fgh(ns) is:
            f      gh        ⁡          (              n        s            )        =      {                            0                                      group            ⁢                                                  ⁢            hopping            ⁢                                                  ⁢            function            ⁢                                                  ⁢            being            ⁢                                                  ⁢            off                                                                          (                                                ∑                                      i                    =                    0                                    7                                ⁢                                                      c                    ⁡                                          (                                                                        8                          ⁢                                                                                                          ⁢                                                      n                            s                                                                          +                        i                                            )                                                        ·                                      2                    i                                                              )                        ⁢            mod            ⁢                                                  ⁢            30                                                group            ⁢                                                  ⁢            hopping            ⁢                                                  ⁢            function            ⁢                                                  ⁢            being            ⁢                                                  ⁢            on                              
In a radio frame, ns=0, 1, . . . , 19; c(i) is a pseudo-random sequence which is initialized at the beginning of each frame, the initial value is
            c      init        =          ⌊                        N          ID          cell                30            ⌋        ,and NIDcell is a physical layer cell ID.
The PUCCH and the PUSCH have the same group hopping pattern but different sequence-shift patterns.
The sequence-shift pattern fssPUCCH of the PUCCH is:fssPUCCH=NIDcell mod 30
The sequence-shift pattern fssPUCCH of the PUSCH is:fssPUSCH=(fssPUCCH+Δss)mod 30
where Δssε{0, 1, . . . , 29} is configured by the high layer.
Sequence hopping is only used when the length of the reference signal sequence is MscRS≦6NscRB.
When the length of the reference signal sequence is MscRS<6NscRB, there is only one base sequence with length of MscRS in each group, and the intragroup sequence serial number of the base sequence is v=0.
When the length of the reference signal sequence is MscRS≧6NscRB, there are two base sequences with length of v=0, 1, and the intragroup sequence serial number of the base sequence used in the slot ns is,
  v  =      {                                        c            ⁡                          (                              n                s                            )                                                                                                                                if                    ⁢                                                                                  ⁢                    group                    ⁢                                                                                  ⁢                    hopping                    ⁢                                                                                  ⁢                    function                    ⁢                                                                                  ⁢                    is                    ⁢                                                                                  ⁢                    off                                    ,                                                                                                      sequence                  ⁢                                                                          ⁢                  hopping                  ⁢                                                                          ⁢                  function                  ⁢                                                                          ⁢                  is                  ⁢                                                                          ⁢                  on                                                                                          0                          otherwise                    
where in a radio frame, ns=0, 1, . . . , 19, and c(i) is a pseudo-random sequence which is initialized at the beginning of each frame, and the initial value is
      c    init    =                    ⌊                              N            ID            cell                    30                ⌋            ·              2        5              +                  f        ss        PUSCH            .      
A DM RS sequence rPUSCH(•) for the PUSCH is defined asrPUSCH(m·MscRS+n)=ru,v(α)(n)wherem=0,1n=0, . . . ,MscRS−1andMscRS=MscPUSCH 
m=0, 1 correspond to two slots in one subframe (with the length of 1 ms) respectively.
In the slot ns, the cyclic shift quantity α is:α=2πncs/12wherencs=(nDMRS(1)+nDMRS(2)+nPRS(ns))mod 12
nDMRS(1) is configured with high layer parameters, and nDMRS(2) is configured with system signaling,nPRS(ns)=Σi=07c(8NsymbUL·ns+i)·2i 
where in a radio frame, ns=0, 1, . . . , 19; c(i) is a pseudo-random sequence which is initialized at the beginning of each frame, and its initial value is
      c    init    =                    ⌊                              N            ID            cell                    30                ⌋            ·              2        5              +                  f        ss        PUSCH            .      
The structure of the DM RS of the PUSCH is shown in FIG. 3 and FIG. 4. After the sequence rPUSCH(•) is multiplied by a magnitude scaling factor βPUSCH, starting with rPUSCH (0), the sequence rPUSCH(•) is mapped to the same physical resource block set for corresponding PUSCH transmission. When the sequence rPUSCH(•) is mapped to RE (k,l) of a subframe, the mapping is performed first in frequency domain (k) and then in time-domain (l) in an ascending order of k and l. The DM RS in each slot is always located at the fourth one (l=3) of seven normal CP symbols or the third one (l=2) of six extended CP symbols in this slot.
Since the DM RSs of the PUSCH of each UE are sent within the transmission bandwidth of the PUSCH of the UE and the PUSCHs of all UEs in the cell are orthogonal with each other in frequency domain, the corresponding DM RSs are orthogonal with each other in frequency domain as well.
The LTE-Advanced system (LTE-A system for short) is a next-generation evolution system of the LTE system. As shown in FIG. 5, the LTE-A system extends the transmission bandwidth using the carrier aggregation technology, and each aggregated carrier is called as a component carrier. A plurality of component carriers might be continuous or non-continuous, and they might be in the same frequency band or different frequency bands.
During carrier aggregation, when a UE sends the PUSCH on a plurality of component carriers, how to send the demodulation reference signals (DM RS) has become a problem to be solved urgently.
In addition, in the LTE-A systems, the PUSCH of a UE within a component carrier might use continuous or non-continuous resource allocation method according to instruction of the system signaling. By continuous resource allocation, it is meant that localized resource allocation method, i.e., a PUSCH transmit signal of the UE occupies a section of continuous bandwidth within a component carrier; by non-continuous resource allocation, it is meant that the PUSCH transmit signal of the UE occupies multiple sections of bandwidths within a component carrier, and these sections of bandwidth are non-continuous, and each section of bandwidth contains a set of continuous PRBs.
For the PUSCH in the non-continuous resource allocation, how to send the demodulation reference signals (DM RS) has become a problem required to be solved.